This invention relates to a radio communication system searching method for a portable telephone terminal for selecting, when a plurality of radio communication systems having different carrier frequencies are present in a same area, a suitable one of the radio communication systems.
In radio communication systems for portable telephone terminals (including mobile telephone terminals) of the AMPS (Advanced Mobile Phone System) system adopted in North America, Australia and so forth, normally two different types of radio communication systems having different carrier frequencies are used in a same area so that various services by the two systems are available in the area. The two types of radio communication systems are generally classified from each other and managed depending upon whether the enterprise which makes the body of management is a radio company or a main line company. In the following description, a radio communication system managed by a radio company will be hereinafter referred to as a radio company system, and a radio communication system managed by a main line company will be hereinafter referred to as a main line company system.
The two types of systems will be described in detail below with reference to FIG. 6. In FIG. 6, a radio company system is arranged in each of areas defined by broken lines while a main line company system is arranged in each of areas defined by solid lines. In particular, a radio company system managed by a company A is arranged in an area 101; a main line company system managed by another company B is arranged in another area 102 which is a substantially same area as the area 101; another radio company system managed by the company A is arranged in a further area 103 which is different and spaced away from the area 101; another main line company system managed by a further company C is arranged in a still further area 104 which is a substantially same area as the area 103; a further radio company system managed by a still further company D is arranged in a yet further area 105 which is different and spaced away from the areas 101 and 103; and a further main line company system managed by a yet further company E is arranged in a yet further area 106 which is a substantially same area as the area 105.
When the systems are managed in such a manner as shown in FIG. 6, if a particular user of a portable telephone terminal executes a contract with the radio company system managed by the company A in the area 101, then the radio company system arranged in the area 101 makes a home system to the portable telephone terminal user. While the main line company system arranged in the substantially same area 102 and managed by the company B is present in the area 101 since the main line company system of the company B is a system outside of the contract to the user who is under contract with the radio company system of the company A, naturally the charge for usage of the main line company system is rather high.
By the way, when the user which is under contract with the radio company system of the company A in the area 101 moves from within the area 101 to any one of the other areas 103 to 106, any one of these systems is outside the contract to the user. However, it is supposed that, as seen from FIG. 6, there may possibly be the same company as the particular company which manages the radio company system with which the user is under contract such as, for example, the company A which manages the radio company system in the area 103, or an affiliated company of the particular company such as, for example, the company D which manages the radio company system in the area 105.
While the system which is managed by such company is not the home system to the user, the user can use the system at a rather lower charge than the charge in ordinary roaming (to access a system other than the system with which the user is under contract, that is, a main line company system when the user is under contract with a radio company system, or a radio company system when the user is under contract with a main line company system). Also the charge system for users under contract with a main line company system is substantially similar to that for the user of the radio company system described above.
Accordingly, where the management areas of the systems are constructed as seen in FIG. 6, a portable telephone terminal of a user under contract with a radio company system is only required to have a function of preferentially searching a radio company system or of searching only a radio company system while a telephone terminal of another user under contract with a main line company system is only required to have a function of preferentially searching a main line company system or of searching only a main line company system.
In short, since the management area configuration of the systems is systematic as seen from FIG. 6, a portable telephone terminal is only required to preferentially search a radio communication system as with which the user is under contract or of searching only such radio communication system can be set by operation of the user itself (for example, by operation of keys). More specifically, if setting for preferentially searching a radio communication system with which the user is under contract is performed once, then a system favorable to the user can always be selected without modifying the setting once more.
In recent years, however, as the demand for portable telephones increases, the utilization areas of radio communication systems expand and also the number of radio communication systems continues to increase. Also excessive competition among radio communication systems is increasing.
Also, due to an influence of such expansion and increase of and excessive competition among radio communication systems, the classification of radio communication systems between a radio company system and a main line company system is disordered, and such a form (refer to FIG. 7 which will be hereinafter described) that a same enterprise manages, in an area, a radio communication system of the same carrier frequency as that of the radio company system described above, but manages, in another area, another radio communication system of the same carrier frequency as that of the main line company system described above occurs. The function of searching a radio communication system provided for conventional telephone terminals cannot cope with the situation.
Therefore, it is desired that, while a user itself understands the arrangement of radio communication systems, it can make use of a function of selecting a portable telephone terminal to set and modify criteria for a search in accordance with a position wherein the portable telephone terminal is used.
Further, if radio communication systems of the same company type are employed in adjacent areas, then three or more radio communication systems may be present as a result of overlapping of such systems in a region in which only two radio communication systems have been present till then.
In such a situation just described, since a portable telephone terminal of the AMPS specification preferentially searches and accesses a radio communication system which is highest in intensity in radio waves (electric field), depending upon the condition of the radio waves, the user may not possibly access a radio communication system best to the user (in short, a radio communication system which is the most advantageous to the user in terms of the charge for using). In the worst case, even if the user is in the area under contract (at home), it cannot access even the home system.
For example, the situation wherein radio communication systems of the same company type are present in adjacent areas and a same enterprise manages radio communication systems of different company types and the situation wherein a user cannot access its home system while it is in an area of the home system will be described in more detail with reference to FIG. 7. It is to be noted that, also in FIG. 7, any region defined by a broken line is an area in which a radio company system is incorporated, and any region defined by a solid line is an area in which a main line company system is incorporated.
Referring to FIG. 7, a radio company system managed by a company F is arranged in an area 201; another radio company system managed by another company G is arranged in another area 202 adjacent to the area 201; a further radio company system managed by a further company H is arranged in a further area 203 adjacent to the area 202; a still further radio company system managed by a still further company I is arranged in a still further area 204 adjacent to the areas 202 and 203; a main line company system managed by the company I is arranged in a yet further area 205 which is substantially the same as the area 201; another main line company system managed by the company F is arranged in a yet further area 206 which is substantially the same as the area 202: and a further main line company system managed by a yet further company J is arranged in a yet further area 207 which almost overlaps with the area 203.
It is assumed that, where the systems are managed as seen in FIG. 7, a user of a portable telephone terminal who is, for example, under contract with the radio company system managed by the company F in the region 201 accesses at a position P substantially on the boundary between the areas 201 and 202 shown in FIG. 7. In this instance, at the position P, not only the radio company system managed by the company F but also the radio company system managed by the company G (area 202) and the main line company system managed by the company I (area 205) are present in an overlapping relationship. Here, it naturally is the best choice, in short, the most advantageous in terms of the charge for using, to the user whose home system is the radio communication system of the area 201 to search and access the radio communication system of the area 201 which is the home system of the user.
However, since a portable telephone terminal of the AMPS specification preferentially searches and accesses that radio communication system which is highest in intensity of radio waves as described above, even if the radio communication system of the company type with which the user is under contract (in this instance, the radio company system) is preferentially searched, radio waves of the radio company system managed by the company G in the area 202 may possibly be more intense, depending upon the condition of radio waves, than radio waves of the radio company system managed by the company F in the area 201 which is the home system of the user. Thus, while the user is in the area 201 in which the home system of it is arranged, it may search and access the radio company system managed by the company G which is not the home system of the user.
Recently, also, a radio communication system with which, even when this is a roam system (a radio communication system of a different company type from that (carrier frequency) of the radio communication system with which the user is under contract), a service is available at a low charge similar to that of the home system has been provided as a result of the intensification of the competition for acquisition of users, and repletion of a radio communication system searching function on the portable telephone terminal side is demanded earnestly.
It is an object of the present invention to provide a radio communication system searching method by which radio communication systems can be searched in order beginning with a radio communication system which is the most advantageous to the user, to eliminate the problems of disorder of company types of radio communication systems and system selection involved in adjacent systems of a same company type and enhance economy.
It is another object of the present invention to provide a radio communication system searching method wherein the time required to search a radio communication system advantageous to a portable telephone terminal is minimized.
It is a further object of the present invention to provide a radio communication system searching method wherein preferential order numbers for optimum selection can be set arbitrarily to a portable telephone terminal in accordance with a demand of the user or an area in which the portable telephone terminal is used so that the portable telephone terminal can cope readily with such a case wherein the user of the portable telephone terminal moves over a wide range.
In order to attain the objects described above, according to an aspect of the present invention, there is provided a radio communication system searching method for a portable telephone terminal for selecting, when a plurality of radio communication systems having different carrier frequencies are present in an overlapping relationship in a same area, one of the radio communication systems, the portable telephone terminal including searching means for searching the radio communication systems and preferential order registration means for registering preferential order numbers of the radio communication systems in advance into the portable telephone terminal, the searching method comprising the steps of searching, by the searching means, a home radio communication system of a predetermined carrier frequency with which the portable telephone terminal is under contract, and successively searching, when the home radio communication system has not been searched out, by the searching means, the remaining radio communication systems in accordance with the preferential order numbers registered in advance in the portable telephone terminal by the preferential order registration means.
At the step of successively searching the radio communication systems in accordance with the preferential order numbers by the searching means, the one of the radio communication systems which has a different carrier frequency from the predetermined carrier frequency of the home radio communication system may be searched preferentially. Or, when the successive searching of the radio communication systems in accordance with the preferential order numbers by the searching means fails to search out a relevant radio communication system, the one of the radio communication systems which has the same carrier frequency as the predetermined carrier frequency of the home radio communication system may be searched preferentially by the searching means.
The preferential order numbers may be determined in accordance with the charge for using of circuits which is advantageous to the portable telephone terminal.
The preferential order registration means may be provided on a body of the portable telephone terminal. In this instance, an operation of registering each of the preferential order numbers by the preferential order registration means is performed by operating keys provided on the portable telephone terminal to input an ID number and a preferential order number of a radio communication system to be registered. Further, the preferential order registration means may include storage means for storing an ID number of a radio communication system inputted by such registering operation in accordance with a preferential order number inputted subsequently to the ID number.
According to another aspect of the present invention, there is provided a radio communication system searching method for a portable telephone terminal for selecting, when a plurality of radio communication systems having different carrier frequencies are present in an overlapping relationship and some of the radio communication systems having a same carrier frequency are managed in adjacent areas by different management system companies, one of the radio communication systems, the portable telephone terminal including searching means for searching the radio communication systems and preferential order registration means for registering preferential order numbers of the radio communication systems in advance into the portable telephone terminal, the searching method comprising the steps of searching, by the searching means, a home radio communication system of a predetermined carrier frequency in a predetermined area with which the portable telephone terminal is under contract, and successively searching, when the home radio communication system has not been searched out, by the searching means, the remaining radio communication systems in accordance with the preferential order numbers registered in advance in the portable telephone terminal by the preferential order registration means.
At the step of successively searching the radio communication systems in accordance with the preferential order numbers by the searching means, the one of the radio communication systems which has a different carrier frequency from the predetermined carrier frequency of the home radio communication system may be searched preferentially. Or, when the successive searching of the radio communication systems in accordance with the preferential order numbers by the searching means fails to search out a relevant radio communication system, the one of the radio communication systems which has the same carrier frequency as the predetermined carrier frequency of the home radio communication system may be searched preferentially by the searching means.
The preferential order numbers may be determined in accordance with the charge for using of circuits which is advantageous to the portable telephone terminal.
The preferential order registration means may be provided on a body of the portable telephone terminal. In this instance, an operation of registering each of the preferential order numbers by the preferential order registration means is performed by operating keys provided on the portable telephone terminal to input an ID number and a preferential order number of a radio communication system to be registered. Further, the preferential order registration means may include storage means for storing an ID number of a radio communication system inputted by such registering operation in accordance with a preferential order number inputted subsequently to the ID number.
With the radio communication system searching method, after the preferential order numbers of the radio communication systems are registered in advance into the portable telephone terminal, the home radio communication system to the portable telephone terminal is searched first, and then, when the home radio communication system has not been searched out successfully the remaining radio communication systems are successively searched in accordance with the preferential order numbers registered in advance in the portable telephone terminal. Consequently, the radio communication system searching method is advantageous in that the radio communication systems can be searched successively in order beginning with the one of the radio communication systems which is the most advantageous to the user of the portable telephone terminal. The problems of a disorder of company types of the radio communication systems and system selection involved in an adjacent arrangement of systems of a same company type can be eliminated, and besides, the searching system is very superior in economy.
Further, where, at the step of successively searching the radio communication systems in accordance with the preferential order numbers, that the one of the radio communication systems which has a different carrier frequency from the predetermined carrier frequency of the home radio communication system is searched preferentially, there is an advantage in that the time required to search out a radio communication system advantageous to the portable telephone terminal is reduced remarkably. Similarly, when the successive searching of the radio communication systems in accordance with the preferential order numbers fails to search out a relevant radio communication system, where that the one of the radio communication systems which has the same carrier frequency as the predetermined carrier frequency of the home radio communication system is searched preferentially, similarly the time required to search out a radio communication system advantageous to the portable telephone terminal can be reduced remarkably.
Further, where the preferential order numbers are determined in accordance with the charge for using circuits which are advantageous to the portable telephone terminal, the radio communication systems are successively searched beginning with the one of them which is advantageous in terms of the charge, and accordingly, the economical advantage is very high.
Furthermore, since the keys provided on the portable telephone terminal can be operated to input an ID number and a preferential order number of a radio communication system to be registered and the ID number of the radio communication system can be stored into the storage means of the preferential order registration means provided on the body of the portable telephone terminal in accordance with the preferential order number of it inputted subsequently to the ID number, optimum preferential order numbers can be registered arbitrarily into the portable telephone terminal in accordance with a requirement of the user and/or an area in which the portable telephone terminal is used. Consequently, the radio communication system searching method can cope readily with a case wherein the user of the portable telephone terminal moves over a wide range.
Further objects, features and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts or elements are denoted by like reference characters.